The present invention relates to an encapsulated oil particle comprising a water soluble polymer, an oil and a hydrophobic additive as well as a process for making the encapsulated particle. The encapsulating material is a water-soluble polymer which dissolves when the particle is diluted with or added to water, thereby releasing the oil. The particle is prepared by dehydrating an emulsion of the oil and the water soluble polymer.
It is useful to encapsulate an oil in a water-soluble matrix to deliver an otherwise liquid material in a powder, paste or cream formulation. Encapsulated oil particles are used in powdered beverages, nutritional supplements, pharmaceutical preparations and particulate detergent compositions as well as for delivering scents into disposable articles such as baby diapers or sanitary napkins. Encapsulation can also enhance and prolong the functional characteristics of the encapsulated oils. Products containing oils that have been encapsulated are more easily packaged and retain their functional characteristics longer during storage because the encapsulated oil is protected from degradation by other ingredients in the compositions as well as from atmospheric degradation. Encapsulation is also used to provide sustained release of the oils encapsulated.
There has been a continuing search for methods and compositions which effectively and efficiently deliver oils into an aqueous medium, i.e. delivering a hydrophobic perfume oil to an aqueous laundry solution.
The choice of the encapsulation process for a specific application is based on parameters such as mean particle size required, physical/chemical properties of both the oil and the encapsulating matrix, desired release mechanism, industrial manufacturing scale envisioned, and the process cost. One such method for encapsulating hydrophobic materials is described in Applicants"" co-pending application Ser. No. 09/980,801.
Hydrophobic silica has been used as a starting material in encapsulation processes. U.S. Pat. No. 5,500,223 to Behan et. al., provides a detailed discussion of using hydrophobic silica in a complex coacervation process whereby the silica is dispersed in water, active material is added, and a pH adjustment is followed by addition of a salt or cationic surfactant/polymer to gel the colloidal mixture.
Another method for delivery of perfume in the wash cycle involves combining the perfume with an emulsifier and water soluble polymer, forming the mixture into particles, and adding them to a laundry composition, as is described in U.S. Pat. 4,209,417, Whyte, issued Jun. 24, 1980; U.S. Pat. No. 4,339,356, Whyte, issued Jul. 13, 1982; and U.S. Pat. No. 3,576,760, Gould et al., issued Apr. 27, 1971. However, even with the substantial work done in the industry, a need still exists for a simple, more efficient and effective oil delivery system which can be used to deliver oils in dry compositions.
The present invention relates to an encapsulated oil particle comprising, a water soluble polymer, an oil, and an effective amount of a hydrophobic additive.
The present invention also relates to a process for manufacturing the above described encapsulated oil particle comprising the steps of dispersing an effective amount of a hydrophobic additive into an oil, emulsifying the dispersion into an aqueous solution of a water-soluble polymer, atomizing the emulsion, and dehydrating the atomized emulsion to form an encapsulated oil particle.
It is an object of the invention to provide an encapsulate with less oil present on the surface, increased encapsulation efficiency (increase in the amount of oil encapsulated) and increased physical stability of the encapsulated particle (minimum oil loss over time). It is a further object of the invention to provide increased product yield from the dehydration process (lower amount of product stuck to the wall of the drying chamber) and to increase the drying rate from the dehydration process without additional energy input into the system.
The invention also relates to compositions comprising encapsulated oils as herein described, such as powdered beverages, cosmetics, hair care compositions, foods (coffee, preservatives, colors, sweeteners, enzymes, antioxidants, cross-linking agents), pharmaceuticals (vitamins, drug delivery compositions), personal cleansing, dish wash, hard surface cleaners, parachemical industries (encapsulation of catalysts, release of batericidal agents, coloring agents), agrochemical industry (for release of pesticides), essential oils and fragrances (delayed release, prevention of chemical degradation, incorporation into dry systems, modulation of odor release), and especially granular detergents.
The present invention solves the long-standing need for a simple, cost effective, storage-stable oil delivery system. Further, encapsulated oil-containing compositions have reduced product odor during storage of the composition. The present invention also yields substantial monetary savings in the dehydration process.
All percentages, ratios, and proportions herein are on a weight basis unless otherwise indicated. All documents cited are hereby incorporated by reference in their entirety.